Sight distance rules meant for safety

The view of eastbound traffic on Flint Hill Road from a car on Long Court in… (DAN HARTZELL, THE MORNING…)

August 30, 2012|Dan Hartzell | The Road Warrior

Q: What are the state rules for sight triangles on the roadways and right of ways? Many people have been placing obstructions in these areas, making it extremely difficult to see when driving. You recently discussed advertising signs being placed in the highway sight lines, but what methods or measurements are used to determine the allowable sight distances? Sight lines should be kept clear at all times.

— Debra Bakos, Bethlehem

Q: Who might be responsible for cutting back brush and trees at a dangerous intersection? Route 873 at Best Station Road in Washington Township (Lehigh County) is one example. It's a nasty configuration to begin with (especially for left turns onto Best Station), made worse by the growth of roadside brush and trees. Is PennDOT responsible for vegetation removal, or is it the property owner?

— Ron Rutt, Washington Township

Q: Who is responsible for maintaining a clear sight line where a state road and a township road intersect? For northbound drivers on Long Court at Flint Hill Road in Heidelberg Township, corn and weeds growing on the southwest corner make it impossible to adequately see until you're already in the eastbound lane of Flint Hill.

— Ronald Mohr, Lynn Township

A: David Robinson of Washington Township also emailed recently to suggest that trimming is needed at Route 873 and Best Station Road, a dangerous intersection that we explored a few years ago. PennDOT officials said they diligently try to keep the sight lines clear along this sharply curved intersection.

Municipalities are responsible for clearing the traffic sight lines on their roads, while PennDOT handles state roads, interstates and other limited access highways.

Government employees are supposed to remove only growth within the public rights of way, though sometimes precise boundary locations are unclear. PennDOT or municipalities sometimes compensate property owners for damage to trees or plantings that turned out to be on private property, though PennDOT spokesman Ron Young said such instances are rare.

Property owners are supposed to maintain growth on their land such that it does not obstruct sight lines. In cases when state or municipal officials determine that obstructions pose safety hazards, they notify owners that the plants should be trimmed. Young said property owners almost always comply. "Nobody wants to make the roads less safe," he said — or incur unnecessary liability, I'm sure.

Turning to the Flint Hill/Long Court intersection, you're right, Ronald, the corn blocks the westward view, along with the utility pole, guy wires and a road sign to a lesser degree. I suppose Heidelberg officials could ask the farmer to make an early harvest of just enough corn to clear the way, and to refrain from planting that small section next year.

At the same time, I'm happy to see there's some corn surviving somewhere in the country, given this season's drought conditions, the ethanol demand draining our tank of maize, and other challenges. In addition, the traffic load at the juncture of these two 40 mph rural lanes seems as light as my tiny Fiat 500, in part because Long Court is a dead end road to the south. Still, it's true, the obstructed view poses a danger that could be avoided.

There's always conflicting traffic between the need to keep traffic sight lines and road signs clear for motorists, and the desire to plant and retain as much greenery as we can in a world that seems to be losing it too quickly. States and municipalities try to map a middle-road coarse, without hope of pleasing everyone. I only wish they'd try to steer away from what seems an increasing use of herbicides for the task, even if old-fashioned cutting methods cost more.

The calculation methods for determining safe sight distances are more complex than I would have thought, Debra. Here's the shortcut route.

There are four sight distance categories: at intersections, and for passing, stopping, and decisions. Stopping and passing are relatively easy — how much space is needed to pass safely or stop in time?

According to PennDOT documents, decision sight distance "is the distance needed for a driver to detect an unexpected or otherwise difficult-to-perceive information source or condition in a roadway environment that may be visually cluttered, [to] recognize the condition or its threat potential, [to] select an appropriate speed and path, and [to] initiate and complete the maneuver safely and efficiently."

Among other examples, PennDOT engineer Tom Walter cited the distance needed to recognize that traffic will merge, determine whether there's conflicting traffic (the decision), and then to execute the merger; or to see which is the E-ZPass lane and enter it safely.